Vulcanized rubber joint



r Feb 24, 1942' v is. v. MlTczl-m- LL VULGANIZED RUBBER JOIYNT Filed Aug. 12, 1959 75, 20 y ron VM/-L'pcke/L,

controlling the heat, all

Patented Feb. 24, 1942 UNITED STATES PATENT OFFICE Vvultoaruzrzn numana JOINT Byron v. Mitchell, Jamaica, N. Y. Application vAugust 12, 1939, Serial No. 289,851 z claims. (cl. 12-142) This invention relates to vulcanized rubber joints and' method of forming the same.

The primary/object of the inventionis to form or produce a vulcanized rubber joint wherein the -rubber ,is vulcanized, in situ, by the application of heat interiorly of the body of rubber. A further object of the invention is to provide a vulcanized rubber joint wherein the rubber constituting the joint is mechanically linterlocked with the body in which the joint is formed.

A still further object is to provide la vulcanized rubber joint especially adapted for use 'in connection with leather articles in that the heat which is fapplied canizlng step may not to have 'any detrimental effect on the leather.

A still further object oi the invention is to provide a vulcanized rubber jointfor securing the sole of a shoe to the upper of the shoe.

Still another object is to provide a vulcanized rubber joint between the sole of a shoe and the upper of the shoe to form awater-tight joint or seam connecting the sole and upper.

A still further object vide a shoe sole with a length of vrubber exposed at one surface thereof, the rubber being embedded to the rubber during the vulin the sole and vulcanized, in situ, as 'well as being mechanically interlocked. More specifically, the invention contemplatesv a method of Joining a length of rubber in a body, particularly aA shoe sole, by embedding balength of raw rubber in the shoe sole with a heating element, for instance, an electrical conductor of high" electrical resistivity embedded in the rubberf, whereby heat for vulcanizing the raw rubber is applied" thereto internally "and, by' accurately adjacent leather is eliminated. In the .preferred method, theraw .rubber is placed in a channel formed in the leather sole, the side walls of the that, in cross-section,

channel being undercut so therubber will. be dove-tailed into the leather to thus form a mechanical'-interlock between the rubber and leather. f

-Witnthese and other objects in view,.the invention consists in certain'details of construction and combinations and arrangements of parts, all aswllhereinafter be more fully described, and

the novel features thereof particularly pointed out inthe appended claims.

In the accompanyingdrawing-- I e Figure-1 is a perspective view illustrating the ljheel of ashoe having the rubber sole secured to l the leather portion o be accurately controlled so asof the invention is to pro# danger of damaging the i canizing rubber can,

canized rubber joint for securing the sole to thel upper; l

Fig. 3 is a bottom plan View of a shoe sole having a strip of vulcanized rubber joined thereto by being embedded therein, although being exposed at the tread surface ofthe sole; and

Fig). 4 is a sectional view on the line 4 4 of Fig. l

Due to the fact that the heat required for vulpractically destroy the tissues or fibres of leather, the present-invention is especially adapted for joining vulcanized rubber in leather articles and, particularly, the soles of shoes although, as will hereinafter be described, certain-phases of the invention may be advantageously used in providing a vulcanized rubber joint between two I3, while a similtr Joint bodies of rubber.

Referring to Fig. l, there is illustrated the heel of a. shoe consisting of a layer of leather I0, on which are superimposed layers of rubber Il and I2. 'Ihe layer of rubber Il is secured to the layer of leather I0 by a vulcanized rubber joint IllEL is formed between the two layers of rubber Il these joints, the surfaces be -joined are channeled,

of the -heel sections to with the channels in each two juxtaposed sections located so as to register with one another, after which the channels in each two members are filled with uncured rubber in which there is embedded a heating element I4. Preferably, this heating element is in the form of an electrical conductor of high electrical resistivity, so that by passing an electric current through the conductor heat an be generatedinteriorly of the raw rubber to raise the latter tovvulcanizing temperature. It will be appreciated that the heat generated in this fashion can be' accurately controlled'and, hence, only sufljlcient heat will be generated Within the` rubber to properly vulcanize the latter. In other words, as soon as the rubber is properly vulcanized, the heating step can be terminated, so

that no detrimental effects are produced on the Aheels, it is also preferred to so form them that the rubber, when vulcanized, will be wedged in the respective sections. For instance, the side walls of the channels may be undercut, as illusf` the heel by vulcanized 56 trated, to produce a dove-tailing effect. In actual under various conditions,v

and l2. In forming' practice, this mode of forming a vulcanized rub-4 ber joint between the sole portion of a shoe and the upper of the shoe has proven highly advantageous, particularly in the repair of rubber footwear, for instance, rubber boots. In this connection, it might be added that, while'only the heel portion of an article of footwear is shown in Fig.`1, it will be understood that the s ole proper ofv a rubber boot can be repaired inthe same manner as the layer of rubber I2 is secured to the layer of rubber I I in the heel illustrated in Fig. 1'.

Amodied form of the invention is illustrated in Fig. 2 in connection with producing a watertight seam or joint between a leather sole I5 and the leather upper I 6 of a shoe. In accordance with usual shoe manufacturing practices, the lower edge of the upper I 6 is turned inwardly but, in accordance with the present invention, there is attached to this inturned portion a tape or covering of rubberized fabric I1. This rubf berized tape or fabric .preferably covers both surfaces of the inturned portion of the leather upper and may be stitched to the upper as indicated at I8. As in the embodiment of the invention shown in Fig. 1, the sole I5 has an undercut channel lpreferably having undercut side walls,

and filling this channel with a mass of uncured lrubber 20, in which vthe heating element Il is embedded. By raising the temperature of the uncured rubber to the proper degree of heat v through the medium of heating element Il, the

' again, heating of the rubber is vulcanized, in situ, in the sole. Here. uncured rubber from its interior and the accurate control of the heat so applied will prevent the leather being damaged.

Also, attachment of the vulcanized rubber to the Isole is enhanced by the dove-tail cross-se/ction of the channel forming a mechanical interlock bechannel I9 extending around the upper surface thereof and, in forming this joint, the channel I9 is filled with uncured rubber 20, in which there is embedded the heating element I4. Thus, the upper surface of the uncured rubber 20 is exposed so that it can be forcedinto contact with what would otherwise be the exposed surface of the rubberized tape or fabric I1. With the sole and upper positioned against one another in this fashion and with the proper pressure, the

`uncured rubber is raised to vulcanizing temperature through'the medium of the heating element I4 which, as in the previous case, is preferably in the form of an electrical conductor' arranged in the coil extending through the uncured rubber or along the channel I9. If desired, a rubber cement may be applied to the surface of the leather upper I6 before the rubberized fabric I1 is sewn thereon but, in any event, when the vulcanizing step has been carried on the proper length of time, a thoroughly vwater-tight seam or joint will be formed due to the fact that the heat generated in element I4 vwill effect vulcanization of the rubber in the rubberized fabric I1. It will be understood that the interior construction of the shoe, such as the insole, forms no essential part o1' the present invention and, hence, this interior portion has been more or less diagrammatically illustrated.

Figs. 3 and 4 illustrate afurther embodiment of thel invention as practised in providing a leather shoe sole I5 with anti-slipping surfaces. In this instance, the joint is produced by forming a channel in the wearing surface of the sole, the

tween the vulcanized rubber inlay and the sole. While a continuous, vulcanized rubber joint or inlay is illustrated, it will be understood that the body of rubber need not be of the particular shape shown, nor continuous.

While it is preferred that a lamentarycoiled electrical conductor be used for generating heat interiorly of the raw rubber, it will be understood that this heating element may heat the rubber by conduction. For instance, a metallic filament embedded vin the uncured rubber may be heated externally of the body of rubber and the heat units transmitted to the rubber by conduction. IIn each instance, the heat is applied to the uncured rubber interiorly so that, notwithstanding the fact that the rubber is vulcanized. in situ, the heating step can be accurately controlled to thoroughly vulcanize the rubber without unduly heating the surrounding material which, as before stated, isof importance where the rubber is being vulcanized in a leather body.

lWhat I claim is:

1. 'I'he met of forminga water-tight joint between the leather sole and the upper of a shoe, whichV consists in embedding a strip of uncured rubber around the sole adjacent the edge thereof with an electrical conductor embedded in said rubber', securing a length of rubberized fabric to the upper adjacent the edge thereof, positioning said upper on the sole with said rubberized fabric interposed between the upper and uncured rubber, and passing an electric current' through said electrical conductor to subject the-rubber and fabric to a vulcanizing temperature.

. 2. The method of forming a water-tight joint` BYRON vf MITCHELL. 

